Is it best to buy an iPhone 4 now, or wait until the iPhone 5 launches? PC Advisor investigates.

The Apple iPhone is one of the most popular smartphones in the world to date. If you haven't already got your hands on the iconic device, then we guarantee that you're either currently considering opening your wallet ready to hand over your hard earned cash in return for the shiny device, or you have done so in the past.

One of the questions I get asked most by friends, family and our readers is 'should I buy an iPhone 4 now or wait until the iPhone 5 comes out?'

See also Apple iPhone 5 launch: as it happens

iPhone 4 or iPhone 5?

It's worth pointing out that Apple has still not confirmed it is planning to release a new version of the iPhone. However, speculation is mounting on the web (check out our iPhone 5 rumour round-up for all you need to know) and with the recent loss of an Apple smartphone prototype in a bar in San Francisco, we can make an educated guess that it's coming, and hopefully sometime soon.

Another indicator that the iPhone 5 is on its way is the reduction of pay monthly iPhone tariffs from mobile networks. Compared to the time of the iPhone 4 launch, when Orange was offering the iPhone 4 for free on a £75 per month contract that came with unlimited calls and texts, the operator now has a deal available that will give Brits a free iPhone 4 along with 1,200 minutes of calls and unlimited texts and data for £45 per month.

Likewise, Vodafone was offering the 16GB Apple iPhone 4 for free on a two-year £60 per month contract with 3,000 minutes, unlimited texts, 1GB of data, 1GB of Wi-Fi access and 5MB of European data roaming per day. Now, the network is offering it for free on a £41 per month tariff with 900 minutes, unlimited texts and 750MB of data.

Similarly, at launch, O2 and T-Mobile were also both offering the 16GB iPhone 4 for free to Brits that opted for a £60 per month, two-year contract, but it's now available at no cost on a £42 per month contract and £40.85 tariff respectively.

The fifth of the UK's major mobile networks, 3 has also followed suit and reduced its iPhone tariff price. Originally, 3 customers could get their hands on a free 16GB iPhone 4 on the £45-per-month contract that included 2,000 minutes of calls of landlines and other mobile networks, 5,000 minutes of calls to other mobile users on the 3 network, 5,000 texts and a data allowance of 1GB. However, the price has now dropped by £5.

These are all certainly value for money deals, so should you take the plunge or hang on for the new handset?

NEXT PAGE: How the specifications of the iPhone 4 and iPhone 5 will differ